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  1. C# Driver
  2. CSHARP-4705

ExpressionNotSupportedException with projection expression

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Details

    • Icon: Bug Bug
    • Resolution: Works as Designed
    • Icon: Unknown Unknown
    • None
    • 2.20.0
    • None
    • None
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      2. Would you like the user to see examples of the syntax and/or executable code and its output?
      3. Which versions of the driver/connector does this apply to?

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      1. What would you like to communicate to the user about this feature? 2. Would you like the user to see examples of the syntax and/or executable code and its output? 3. Which versions of the driver/connector does this apply to?

    Description

      Summary

      After upgrading the MongoDB C# driver from 2.15.0 to 2.20.0, I am getting ExpressionNotSupportedException for one of my queries. I am running MongoDB 5.0.18.

      How to Reproduce

      I have the following object:

       

      public class UnlockableModel
      {
          [BsonId]
          public Guid profileId { get; set; }
          public Dictionary<String, List<String>> entries { get; set; }
      }

      The following query will fail with ExpressionNotSupportedException:

      List<string> categories = new List<string> {"Test"};
       
      var filter = Builders<UnlockableModel>.Filter.Eq(model => model.profileId, profileId);
      var options = new FindOptions<UnlockableModel>
      {
          Projection = Builders<UnlockableModel>.Projection.Expression(p => new UnlockableModel
          {
              profileId = p.profileId,
              entries = (p.entries != null) ? new(p.entries.Where(kvp => categories.Contains(kvp.Key))) : new()
          })
      };
       
      var result = await _unlockableCollection.FindAsync(filter, options);

      Downgrading the connection to LinqProvider.V2 fixes the issue:

      var connectionString = "mongodb://localhost";
      MongoClientSettings settings = MongoClientSettings.FromConnectionString(connectionString);
      settings.LinqProvider = LinqProvider.V2;

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            robert@mongodb.com Robert Stam
            loris.blanchon@ubisoft.com Loris Blanchon
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            Dates

              Created:
              Updated:
              Resolved: